Why we need models in software development?

Software development is not a simple process. It requires a deep analysis.  Engineering deals with the economical use of all available resources. There are some certain practices in each engineering discipline. Trying to invent the wheel each time is not required. As the software is complex and a large percentage of the software projects are doomed to failure, models proved to be successful are the key of successful software projects. Software technology needs engineering discipline to be able to repeatedly and economically produce reliable software intensive products and services.

Furthermore, measuring the quality of the software produced is a must. For this purpose, models such as CMM are developed. Together with the improved industry standard software processes, these models ensure quality in software.